Flip chip bonding is a process for interconnecting semiconductor devices, components, or dies to a circuit board, wafer, or substrate. The semiconductor devices have solder bumps that are deposited on the chip pads on the top surface of the semiconductor devices. The semiconductor devices are then flipped over by a flip arm or actuator so that the top surface faces down, and the chip pads are aligned with the pad surface of the substrate. The bond arm moves to bond the semiconductor devices onto the substrate, and the solder is reflowed to complete the interconnections.
In the flip chip bonding process, control of the tilt angle between the semiconductor devices and the substrate, i.e. bond arm tilt, is critical. In an ideal bonding process as shown in FIG. 1A, a bond arm 100 actuates or displaces a semiconductor device 20 having solder bumps 22 towards a pad surface 32 of a substrate 30, wherein the substrate 30 is disposed on an anvil surface or bonding support surface 200 of an anvil or bonding support 202. The solder bumps 22 can bond evenly with the pad surface 32 and the electrical connections between the semiconductor device 20 and the pad surface 32 are complete. However, in a non-ideal bonding process as shown in FIG. 1B, the solder bumps 22 do not bond evenly with the pad surface 32. Thus, if the bond arm tilt is not properly controlled or an acceptable range of bond arm tilt cannot be achieved, problems such as uneven flatness of the solder bumps 22 as shown in FIG. 1B may occur, increasing the risk of cold joints between the semiconductor device 20 and pad surface 32.
An existing method of controlling bond arm tilt is to manually adjust the orientation of the bond arm 100 relative to the bonding support 202, specifically the bonding support surface 200. The adjustment may be by way of turning the bond arm 100 about the x-axis and y-axis, such that the bond arm 100 points differently towards the bonding support surface 200. After adjustment, the bond arm 100 may be mechanically fastened by screws, and the bond arm tilt can be measured and assessed. Repeated adjustments may be needed until the measured bond arm tilt satisfies, meets, or complies with a predefined specification. Moreover, the predefined specification may be tight and fine adjustment of the bond arm tilt may be required after a tool change, e.g. change of a bond collet.
One problem associated with the existing adjustment method is that the repetitive process of mechanical and manual adjustments followed by the tilting measurement is a qualitative one and is time-consuming. There is also a risk of human errors, e.g. due to mechanical adjustment in the wrong direction or misreading of measurements.
Therefore, in order to address or alleviate at least one of the aforementioned problems and/or disadvantages, there is a need to provide a method and system for automatically aligning a bond arm with respect to a bonding support surface, in which there is at least one improvement and/or advantage over the aforementioned prior art.